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Volume 9
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Quantum Beam Sci., Volume 9, Issue 1 (March 2025) – 10 articles

Cover Story (view full-size image): To lead thermal neutrons from a moderator to a sample under investigation, they are sent through neutron guides with reflective surfaces. Elliptical neutron guides are known to transport neutrons with fewer reflections than straight guides, reducing neutron losses. Since true elliptical shapes are tedious to produce, the elliptical shape may instead be approximated by linearly tapering pieces. In this work, we use the neutron simulation package McStas to investigate this approximation for both simple and realistic guide systems. We show that splitting a model elliptical guide into linear pieces with lengths of up to 3 m does not damage transport properties. For one realistic guide system, we show that the elliptical guide can be approximated with pieces 0.5 m in length without detriment to transport properties. View this paper
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4 pages, 193 KiB  
Editorial
Analysis of Strain, Stress and Texture with Quantum Beams, 2nd Edition
by Kenji Suzuki
Quantum Beam Sci. 2025, 9(1), 10; https://doi.org/10.3390/qubs9010010 - 12 Mar 2025
Viewed by 333
Abstract
Welcome to the Special Issue of Quantum Beam Science, entitled “Analysis of Strain, Stress and Texture with Quantum Beams, 2nd Edition” [...] Full article
(This article belongs to the Special Issue Analysis of Strain, Stress and Texture with Quantum Beams, 2nd Edition)
18 pages, 3409 KiB  
Review
Advancements and Challenges in Colloidal Quantum Dot Infrared Photodetectors: Strategies for Short-Wave Infrared, Mid-Wave Infrared, and Long-Wave Infrared Applications
by Lijing Yu, Pin Tian and Kun Liang
Quantum Beam Sci. 2025, 9(1), 9; https://doi.org/10.3390/qubs9010009 - 3 Mar 2025
Viewed by 857
Abstract
Colloidal quantum dots (QDs) have emerged as promising materials for the development of infrared photodetectors owing to their tunable band gaps, cost-effective manufacturing, and ease of processing. This paper provides a comprehensive overview of the fundamental properties of quantum dots and the operating [...] Read more.
Colloidal quantum dots (QDs) have emerged as promising materials for the development of infrared photodetectors owing to their tunable band gaps, cost-effective manufacturing, and ease of processing. This paper provides a comprehensive overview of the fundamental properties of quantum dots and the operating principles of various infrared detectors. We review the latest advancements in short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR) detectors employing colloidal quantum dots. Despite their potential, these detectors face significant challenges compared to conventional infrared technologies. Current commercial applications are predominantly limited to the near-infrared and short-wave bands, with medium- and long-wave applications still under development. The focus has largely been on lead and mercury-based quantum dots, which pose environmental concerns, underscoring the need for high-performance, non-toxic materials. Looking forward, the development of large array and small pixel detectors and improving compatibility with readout circuits are critical for future progress. This paper discusses these hurdles and offers insight into potential strategies to overcome them, paving the way for next-generation infrared sensing technologies. Full article
(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2024)
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14 pages, 5366 KiB  
Article
Investigation of Mn2+-Doped Stearic-Acid Through XRD, Raman, and FT-IR, and Thermal Studies
by Rodrigo M. Rocha, Marinaldo V. de Souza Junior, Luiz F. L. Silva, Paulo T. C. Freire, Gardênia S. Pinheiro, Waldomiro Paschoal, Jr., Francisco F. de Sousa and Sanclayton G. C. Moreira
Quantum Beam Sci. 2025, 9(1), 8; https://doi.org/10.3390/qubs9010008 - 1 Mar 2025
Viewed by 497
Abstract
In this research, we investigated the influence of Mn2+ ions on the packing in stearic acid (SA) crystals through the use of Raman spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The crystals investigated were obtained utilizing the slow evaporation [...] Read more.
In this research, we investigated the influence of Mn2+ ions on the packing in stearic acid (SA) crystals through the use of Raman spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The crystals investigated were obtained utilizing the slow evaporation methodology in a hexane solution under varying manganese (Mn) concentrations sourced from MnSO4 5H2O (0.5, 1.0, 1.5, 2.0, 4.0, and 6.0%). XRD studies indicated that all SA crystals were grown in the Bm form (monoclinic), favoring the gauche conformation in molecular packing. Additionally, crystalline lattice modifications were observed through Raman spectral changes in the low-vibrational energy region. Variations in the intensities and Raman shifts in two lattice vibrational modes, centered at approximately 59 and 70 cm−1, revealed that two types of hydrogen bonds are distinctly affected within the crystalline lattice. Furthermore, the unit cell parameters (a, b, c, and β) were determined via Rietveld refinement, and their behavior was analyzed as a function of Mn concentration. The results indicated that Mn2+ ions exert a strain and deformation effect on the unit cell. Lastly, differential scanning calorimetry (DSC) was employed to evaluate the thermal stability of the Bm form of SA crystals. Full article
(This article belongs to the Section Engineering and Structural Materials)
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14 pages, 2521 KiB  
Article
Dosimetric Study of Flattened Versus Unflattened Filter-Free Medical Linear Accelerator: Experimental Measurements and Monte Carlo Calculations
by Mohammed Halato, Ibrahim I. Suliman, Abdelmonim Artoli, Francesco Longo and Gianrossano Giannini
Quantum Beam Sci. 2025, 9(1), 7; https://doi.org/10.3390/qubs9010007 - 24 Feb 2025
Viewed by 462
Abstract
A dosimetric study compared flattened filter (FF) and unflattened filter-free (FFF) 18 MV medical linear accelerators (LINAC) using BEAMnrc Monte Carlo (MC) calculations and experimental measurements. BEAMnrc MC simulations were initially validated against experimental measurements for an 18 MV FF LINAC, with parameters [...] Read more.
A dosimetric study compared flattened filter (FF) and unflattened filter-free (FFF) 18 MV medical linear accelerators (LINAC) using BEAMnrc Monte Carlo (MC) calculations and experimental measurements. BEAMnrc MC simulations were initially validated against experimental measurements for an 18 MV FF LINAC, with parameters such as the percentage depth dose (PDD) and beam profile measured and calculated per the International Atomic Energy Agency (IAEA) dosimetry protocol TRS 398. Following the validation of the LINAC and water phantom models for MC simulations, BEAMnrc MC calculations were performed to compare the FF and FFF 18 MV LINAC parameters. The results indicate that the BEAMnrc MC accurately simulated the LINAC model, with PDD uncertainties within 2%. Beam flatness differences between the MC simulations and measurements in the plateau region were within 3% and within 2 mm in the penumbra region. The PDD data show that the 18 MV FFF beam delivered a higher dose rate in the buildup region than the FF beam, while beam profile measurements indicate lower out-of-field doses for FFF beams, especially in the 20 × 20 cm2 field. These findings provide crucial dosimetric data for an 18 MV FFF LINAC, which is useful for quality assurance and beam matching, and offer a methodology for quantitatively comparing the dosimetry properties of an individual 18 MV FFF LINAC to reference data. Full article
(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2024)
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18 pages, 5821 KiB  
Review
Intensity Enhancement and Q-Range Extension in Pinhole SANS Instruments with Neutron Focusing Lenses
by Aurel Radulescu
Quantum Beam Sci. 2025, 9(1), 6; https://doi.org/10.3390/qubs9010006 - 12 Feb 2025
Viewed by 697
Abstract
Soft matter and biological materials are characterized by a complex morphology consisting of multiple structural levels that are either hierarchically organized or coexist over a length scale from a few Å up to the size of µm. For a structural characterization of such [...] Read more.
Soft matter and biological materials are characterized by a complex morphology consisting of multiple structural levels that are either hierarchically organized or coexist over a length scale from a few Å up to the size of µm. For a structural characterization of such morphologies, an extended Q-range must be covered in X-ray and neutron scattering experiments. Neutrons offer the unique advantage of contrast variation and matching by D-labeling, which is of great value for the characterization of hydrocarbon systems, which are essentially the constituents of soft matter and biological materials. The combination of ultra- and small-angle neutron scattering techniques (USANS and SANS) on complementary beamlines has long been used for such experimental investigations. However, the combined use of USANS and SANS methods at the same beamline for simultaneous acquisition of scattering data over a wide Q-range is necessary when working with sensitive or expensive samples that require special preparation or in situ treatment during the structural characterization. For this reason, several pinhole SANS instruments have been equipped with focusing lenses to allow additional measurements at lower Q values, in the USANS range. The use of neutron lenses has the additional advantage of enhancing the intensity on the sample by providing the ability to work with larger samples while maintaining the same resolution as in pinhole mode. The experimental approach for using neutron lenses to enhance the intensity and extend the Q-range to lower values than in pinhole mode is presented using examples from studies on the pinhole SANS diffractometers equipped with focusing lenses. Full article
(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2024)
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14 pages, 2844 KiB  
Article
Piecewise Linear Approximation of Elliptical Neutron Guides—A Case Study for BIFROST at ESS
by Daniel Lomholt Christensen, Rebekka Frøystad, Martin Andreas Olsen, Kristine Marie Løfgren Krighaar, Asla Husgard, Mads Bertelsen, Rasmus Toft-Petersen and Kim Lefmann
Quantum Beam Sci. 2025, 9(1), 5; https://doi.org/10.3390/qubs9010005 - 11 Feb 2025
Viewed by 664
Abstract
Previous studies of elliptical neutron guides have shown that they transport neutrons with fewer reflections than traditional guides with a constant cross section, thus reducing neutron losses. True elliptical guides, however, are tedious to produce. Therefore, we use the neutron simulation package McStas [...] Read more.
Previous studies of elliptical neutron guides have shown that they transport neutrons with fewer reflections than traditional guides with a constant cross section, thus reducing neutron losses. True elliptical guides, however, are tedious to produce. Therefore, we use the neutron simulation package McStas to investigate the effect of approximating the elliptical shape by linearly tapering guide pieces. The study concerns both simple model guides and a more complex guide system corresponding to that of the BIFROST instrument, currently under construction at the European Spallation Source (ESS). Our results show that it is possible to split a simple elliptical guide into linearly tapering pieces with lengths of up to 3 m, without sacrificing transport properties. We also find that the piecewise tapering guides in some cases will have a slightly higher neutron transfer than the perfectly shaped guides for shorter wavelengths. For a ballistic guide systems with elliptical expanding and focusing sections, and for the BIFROST guide, linearly tapered pieces of 0.5 m can be used with no cost in transport properties or penalties in form of inhomogeneous phase space, but with significantly lower production costs. Full article
(This article belongs to the Section Instrumentation and Facilities)
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9 pages, 373 KiB  
Article
Model for Proton Acceleration in Strongly Self-Magnetized Sheath Produced by Ultra-High-Intensity Sub-Picosecond Laser Pulses
by Artem V. Korzhimanov
Quantum Beam Sci. 2025, 9(1), 4; https://doi.org/10.3390/qubs9010004 - 20 Jan 2025
Viewed by 861
Abstract
Recently, it has been experimentally shown that the sheath acceleration of protons from ultra-thin metal targets irradiated by sub-picosecond laser pulses of intensities above 1021 W/cm2 is suppressed compared to well-established models. This detrimental effect has been attributed to a self-generation [...] Read more.
Recently, it has been experimentally shown that the sheath acceleration of protons from ultra-thin metal targets irradiated by sub-picosecond laser pulses of intensities above 1021 W/cm2 is suppressed compared to well-established models. This detrimental effect has been attributed to a self-generation of gigagauss-level quasi-static magnetic fields in expanded plasmas on the rear side of a target. Here we present a set of numerical simulations which support this statement. Based on 2D full-scale PIC simulations, it is shown that the scaling of a cutoff energy of the accelerated protons with intensity deviates from a well-established Mora model for laser pulses with a duration exceeding 500 fs. This deviation is showed to be connected to effective magnetization of the hottest electrons producing at the maximum of the laser pulse intensity. We propose a modification of the Mora model which incorporates the effect of the possible electron magnetization. Comparing it to the simulation results shows that by appropriately choosing a single fitting parameter, the model produces results that quantitatively coincide with simulations. Full article
(This article belongs to the Special Issue Laser-Assisted Facilities)
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17 pages, 7192 KiB  
Article
Effect of Dy3+ Ions on Structural, Thermal and Spectroscopic Properties of L-Threonine Crystals: A Visible Light-Emitting Material
by João G. de Oliveira Neto, Otávio C. da Silva Neto, Jéssica A. O. Rodrigues, Jailton R. Viana, Alysson Steimacher, Franciana Pedrochi, Francisco F. de Sousa and Adenilson O. dos Santos
Quantum Beam Sci. 2025, 9(1), 3; https://doi.org/10.3390/qubs9010003 - 13 Jan 2025
Viewed by 769
Abstract
In this study, L-threonine crystals (L-thr) containing Dy3+ ions (L-thrDy5 and L-thrDy10) with varying mass concentrations (5% and 10%) were successfully synthesized using a solvent slow evaporation method. The structural properties were characterized by Powder X-ray diffraction and Rietveld refinement. The data [...] Read more.
In this study, L-threonine crystals (L-thr) containing Dy3+ ions (L-thrDy5 and L-thrDy10) with varying mass concentrations (5% and 10%) were successfully synthesized using a solvent slow evaporation method. The structural properties were characterized by Powder X-ray diffraction and Rietveld refinement. The data revealed that all three samples crystallized in orthorhombic symmetry (P212121-space group) and presented four molecules per unit cell (Z = 4). However, the addition of Dy3+ ions induced a dilation effect in the lattice parameters and cell volume of the organic structure. Additionally, the average crystallite size, lattice microstrain, percentage of void centers, and Hirshfeld surface were calculated for the crystals. Thermogravimetric and differential thermal analysis experiments showed that L-thr containing Dy3+ ions are thermally stable up to 214 °C. Fourier transform infrared and Raman spectroscopy results indicated that the Dy3+ ions interact indirectly with the L-thr molecule via hydrogen bonds, slightly affecting the crystalline structure of the amino acid. Optical analysis in the ultraviolet–visible region displayed eight absorption bands associated with the electronic transitions characteristic of Dy3+ ions in samples containing lanthanides. Furthermore, L-thrDy5 and L-thrDy10 crystals, when optically excited at 385 nm, exhibited three photoluminescence bands centered around approximately 554, 575, and 652 nm, corresponding to the 4F7/2 → 6H11/2, 4F9/2 → 6H13/2, and 4F9/2 → 6H11/2 de-excitations. Therefore, this study demonstrated that L-thr crystals containing Dy3+ ions are promising candidates for the development of optical materials due to their favorable physical and chemical properties. Additionally, it is noteworthy that the synthesis of these systems is cost-effective, and the synthesis method used is efficient. Full article
(This article belongs to the Section Engineering and Structural Materials)
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9 pages, 1820 KiB  
Article
The Movement Mode of the Microworld Particle
by Jinhai Li
Quantum Beam Sci. 2025, 9(1), 2; https://doi.org/10.3390/qubs9010002 - 1 Jan 2025
Viewed by 642
Abstract
Most physicists are dissatisfied with the current explanation of quantum mechanics, and want to find a method to solve this problem. However, this problem has not been solved perfectly up to now. In this paper, annihilation-generation movement (AGM) is developed according to the [...] Read more.
Most physicists are dissatisfied with the current explanation of quantum mechanics, and want to find a method to solve this problem. However, this problem has not been solved perfectly up to now. In this paper, annihilation-generation movement (AGM) is developed according to the electron motion in hydrogen atoms. To verify the AGM, a curved surface that fits the dark fringe of the single-slit diffraction is proposed. Based on the AGM, the wave function of a free electron is rewritten and the double-slit experiment can be understood. Here, we show that the AGM is an alternative physical image that can be used to solve the puzzles of quantum mechanics, such as Heisenberg’s uncertainty principle and steady-state transition. We anticipate that we can find a new way to explain quantum mechanics based on AGM. Full article
(This article belongs to the Special Issue New Challenges in Electron Beams)
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21 pages, 2161 KiB  
Review
On the Similarity and Differences Between Nano-Enhanced Laser-Induced Breakdown Spectroscopy and Nano-Enhanced Laser-Induced Plasma Spectroscopy in Laser-Induced Nanomaterials Plasma
by Ashraf EL Sherbini, AbdelNasser Aboulfotouh and Tharwat EL Sherbini
Quantum Beam Sci. 2025, 9(1), 1; https://doi.org/10.3390/qubs9010001 - 24 Dec 2024
Viewed by 847
Abstract
The interaction of pulsed lasers with matter involving nanomaterials as a pure target or thin layer deposited on a target initiates transient plasma, which shows strong enhancement in a spectral line emission. This domain of research has been explored via two well-established techniques [...] Read more.
The interaction of pulsed lasers with matter involving nanomaterials as a pure target or thin layer deposited on a target initiates transient plasma, which shows strong enhancement in a spectral line emission. This domain of research has been explored via two well-established techniques dubbed NELIBS and NELIPS. These Nano-Enhanced Laser-Induced Breakdown or Plasma Spectroscopy techniques entail similarities as well as differences. The newly defined concept of Nano-Enhanced Laser-Induced Plasma Spectroscopy NELIPS is introduced. Thereupon, certain confusion has arisen from various aspects of the similarities as well as differences between the two techniques. In this article, we will investigate the application of either technique to retrieve relevant data about the enhanced spectral line plasma emission phenomenon. To discriminate between these two techniques, a survey on the nature of the target, the origin of enhancement and prevalent theoretical approaches is presented. In this context, the potential achievements, challenges and expected prospects are comparatively highlighted. This review emphasizes the unique contributions of NELIPS, particularly the advanced approach in nanoscale thermal modeling and spectroscopic applications. Full article
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